A semiconductor memory device (to be referred to as a cross-point memory) using a cross-point nonvolatile memory cell uses a structure in which a rectifying element (for example, diode) and a switching material are arranged in series with each other on one memory cell (for example, see Jpn. Pat. Appln. KOKAI Publication No. 2009-123900). In the cross-point type, memory cells are arranged at cross-points between bit lines and word lines. As the cross-point memory, for example, a resistive random access memory such as an ReRAM (Resistive RAM) or a PCRAM (Phase change RAM) is known.
In the cross-point memory, when a memory cell is gradually shrunk to achieve a large capacity, an aspect obtained after the memory cell is processed becomes as large as about 10, and an insulating film (to be referred to as an interlayer insulating film) to be buried between the memory cells cannot be easily buried. Therefore, an applied film formed by an applying method is used as an interlayer insulating film to try to correct a burying defect.
However, when the applied film is used as the interlayer insulating film, problems such as (1) oxidation of an interconnection and (2) deterioration of a diode are posed. The cause of the oxidation of the interconnection is considered to be a thermal oxidation step performed when N of an organic film serving as an applied film and containing N, C, and Si is replaced with O to form an SiO2 interlayer film.
As regards the deterioration of a diode, impurities of N and C contained in an applied film are present as positive fixed charges, and a band is bent due to an indirect potential effect on the diode caused by the fixed charges. For this reason, a junction leakage defect occurs. In order to prevent an influence caused by the fixed charges, a side wall film having a constant film thickness or more needs to be formed on a side surface of the diode. However, with an increase in capacity, even an applied film is difficult to be buried between memory cells. For this reason, a film which can reduce an influence of fixed charges even though the side wall film is thinned needs to be formed.